Engine starting despite being in Electric mode.

[Phil T]

I have noticed  some strange behaviour. Only when I am approaching the town of Leek on A53 in Battery mode, the road starts to climb and the engine will start. Full Battery and not very steep hill at that stage, traffic at a crawl. I turned on City mode and the engine stopped. Next time I approached I was in City mode and the engine started as before, so next day I tried the same route heater off, no aircon, and City mode. Engine started! At this point the Battery is nearly full. I can go up other steep hills and the car will stay on battery but not on this stretch of road, cold days warm days the same  

[altocumulus]

The only time something similar happened to me was when I was de-misting the front windscreen.

[PeteB]

Not quite the same but my non-plugin Gen 4 sometimes runs the engine when the HV Battery gauge has reached 7 bars after a series of long gentle braking periods on slight downward inclines from 60-70 mph, even when I'm off the accelerator and not braking.

I'm guessing it's something to do with the HV Battery and/or inverter being above a certain temperature after some relatively aggressive charging.  During the time the engine is running, pressing the EV button gets a "cannot ... at this time" type message.

[Anthony Poli]

Not quite the same but my non-plugin Gen 4 sometimes runs the engine when the HV battery gauge has reached 7 bars after a series of long gentle braking periods on slight downward inclines from 60-70 mph, even when I'm off the accelerator and not braking.
I'm guessing it's something to do with the HV battery and/or inverter being above a certain temperature after some relatively aggressive charging.  During the time the engine is running, pressing the EV button gets a "cannot ... at this time" type message.

Worth remembering, just like the symptoms of a clogged Battery fan. [emoji3]


Sent from my iPhone using Tapatalk

[Phil T]

1 hour ago, PeteB said:

Not quite the same but my non-plugin Gen 4 sometimes runs the engine when the HV battery gauge has reached 7 bars after a series of long gentle braking periods on slight downward inclines from 60-70 mph, even when I'm off the accelerator and not braking.

I'm guessing it's something to do with the HV battery and/or inverter being above a certain temperature after some relatively aggressive charging.  During the time the engine is running, pressing the EV button gets a "cannot ... at this time" type message.

I used to get that with my Gen4, lots of long hills around here, you would think that Toyota could have found a way to shut of the charging, rather than turn the engine over to get rid of surplus charge. I was assured that it wasn't actually firing up the engine, unlike mine which is firing up the engine for no apparent reason and using fuel! 

[TheProfessor]

The ICE will fire up for a number of reasons. I suspect in this case it's because your Battery is full. When it's showing all bars full the ICE fires up to allow for engine braking, in lieu of regenerative braking. Otherwise drivers would get confused when they brake gently or take their foot completely off the accelerator and nothing happened at all until they pressed the brake pedal half way and suddenly the friction brakes would come on suddenly and quite hard. You can force this situation by going into B mode, but the Prius will do it automatically when the Battery is completely full.

That being said, several other factors could also be at play here that will cause the ICE to fire up. These include the cabin temperature being lower than the temperature set on the climate control, a large electrical power drain (e.g. rear demister, fan on high, heated seats, etc), or the engine temperature too low (it likes to stay warm to reduce wear). Also, if you are pressing your accelerator more than enough to get the accelerator gauge half way, then also the ICE will activate. Even a gentle hill can require more than 50% accelerator to maintain speed.

[Phil T]

TheProfessor, on the Gen4 I would expect that but this is my 2018 PHEV. Crawling on a slight incline, after setting off doing 10 miles, so lots of energy left in the Battery, all electrics, heater, etc off. Running in City mode and the engine fires up. The other side of Leek heading towards Buxton 10% hill past The Roaches, Battery all the way, no ICE.

[Ten Ninety]

Something similar used to happen with my Gen3 and Auris HSD. Both would occasionally fire up the engine for no apparent reason on the same stretch of road. It wasn't every journey by a long way, but it happened enough times for me to notice how weird it was that both cars did it at pretty much exactly the same point on the road.

I decided it was probably something to do with the Battery conditioning that takes place periodically, as it had no apparent relationship to heater settings or temperature.

My PHEV hasn't done it yet, but I'm sure it will decide to surprise me at some point. HSD moves in mysterious ways!

 

 

[QuantumFireball]

How steep and how long is this hill? I, and other owners of the Gen 1 Plug-in have noticed that during a long ascent, the ICE will kick in after a while despite it not meeting the normal conditions (throttle position, SOC, cabin heating, etc.). It may be something to do with temperatures somewhere, or the Battery current discharge limit meeting a certain threshold which changes dynamically based on temperatures and other factors.

I know of a hill climb near me, about 2.3 km long with a 5% incline, where the ICE will engage during EV mode with only moderate throttle input.

I guess the Gen 2 PHV has similar characteristics.

[Phil T]

 

I will just put this down to a Toyotaism. Turn the radio up so I don’t notice the engine 🤪

[kithmo]

Maybe it's something to do with the earth's magnetic field ?